Prepaid plans get lower priority on carrier infra, as do MVNOs typically. Postpaid/premium is getting premium transit, unfortunately.
If there is any disruption to be had, it is an MVNO that is plugged into all US carriers, as well as satellite offerings, with the ability to pivot around whenever a carrier tries to squeeze the relationship. Google Fi with more carriers and better customer support, Airalo, etc. This enables you to keep your number while the service underneath the account can shift.
Agree, that's the challenge, an abstraction where you maintain the flexibility without the deprioritization. I admit, it may be impossible due to the inherant limitations of the model. With that said, from your link, Google Fi gets a high priority designation on T-Mobile ("QCI 6 goes to all branded plans, both postpaid and prepaid, besides those with Essentials in the name. Google Fi has QCI 6 as well."), so perhaps it's possible.
If there is any disruption to be had, it is an MVNO that is plugged into all US carriers, as well as satellite offerings, with the ability to pivot around whenever a carrier tries to squeeze the relationship. Google Fi with more carriers and better customer support, Airalo, etc. This enables you to keep your number while the service underneath the account can shift.
https://www.airalo.com/global-esim